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Nematosphaeropsis balcombiana
Nematosphaeropsis balcombiana Deflandre and Cookson, 1955
Tax. jr. synonym of Nematosphaeropsis labyrinthea (Ostenfeld, 1903) Reid, 1974, according to Reid, 1974, and Matsuoka, 1983. Wrenn, 1988, retained Nematosphaeropsis balcombiana as a separate species.
This species represents the encysted stage of Gonyaulax spinifera (Claparede and Lachmann, 1859) Diesing, 1866, according to Wall and Dale, 1968.
Holotype: Deflandre and Cookson, 1955, pl.8, fig.5
Locus typicus: Princetown, Victoria, Australia
Stratum typicum: Middle Miocene
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Original diagnosis: Deflandre and Cookson, 1955, p.268
Characters of the genus: shell slightly elliptical, with numerous processes of which the longest approaches half the diameter of the shell. Processes trifurcate, the extremities of the 3 branches joined to neighbouring processes by delicate filaments.
Dimensions: Diameter of shell c. 31 Ám, overall diameter 61 by 56 Ám, length of processes 13-15 Ám (Holotype).
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Comments: Wrenn 1988, p. 139-140
Nematosphaeropsis balcombiana Deflandre & Cookson 1955 (see Plate 7, fig. 3) was described as having a slightly elliptical "shell" (central body) bearing numerous processes, the longest of which approaches half the diameter of the central body. The trifurcate processes are joined distally to neighboring processes by "delicate filaments" (trabeculae). The central body of the holotype is 31 Ám in diameter and the processes range from 13- 15 Ám in length. The distinctive morphologic features of N. balcombiana are its broad, often proximally branched processes, delicate trabeculae of variable width, and the parasutural ridges that clearly express
paratabulation . Wall (1965, 1967) reported N. balcombiana from the Woods Hole, Massachusetts area and the Caribbean Sea. Those from the Woods Hole area he suggested might be identical with Pterosperma
labyrinthus Ostenfeld 1903. This seems unlikely in light of earlier discussions, though this report is hard to assess because no specimens were illustrated. The Caribbean Sea specimens were illustrated (Wall, 1967) and are considered here to be specimens of N. rigida sp. nov. Wall (1967) also reported, but did not illustrate, a "small variety" of what he designated N. balcombiana. These specimens may actually have been specimens of N. Iemniscata.
Comparison. Wrenn 1988, p. 139-140: N. balcombiana differs from:
N. downii by being smaller, having thin, delicate trabeculae and broad, proximally branched processes that are joined proximally by strongly developed parasutural ridges;
N. elegantulum by having clearly expressed paratabulation on the central body and by lacking the complex distal process branching of the latter;
N. Iativittatus sp. nov. by having thin, delicate trabeculae of variable width, broad, proximally branched processes and clearly expressed paratabulation;
N. Iemniscata by having shorter processes that are broad-based and can be branched proximally and by the well-developed parasutural ridges connecting process bases;
N. ? philippotii by having strongly developed parasutural ridges on the central body and broader
processes;
N. pustulosa by having paratabulation expressed by parasutural ridges and by having an elliptical
central body;
N. quinquetrum by having paratabulation expressed by parasutural ridges and by having an
elliptical central body;
N. rigida sp. nov. by having thin delicate trabeculae, broad-based processes that are branched proxi-
mally and well-developed parasutural ridges connecting process bases;
N. scala by having delicate trabeculae that are variable in width and that are not joined to each
other by cross-strands; and
N. singularis by having well-developed parasutural ridges
Stratigraphic Range. N. balcombiana was described from the middle Miocene of Australia. Reported rare occurrences in the Eocene London Clay of England (Williams, 1966; Williams and Downie, 1966) were not illustrated and cannot be assessed.
Tax. jr. synonym of Nematosphaeropsis labyrinthea (Ostenfeld, 1903) Reid, 1974, according to Reid, 1974, and Matsuoka, 1983. Wrenn, 1988, retained Nematosphaeropsis balcombiana as a separate species.
This species represents the encysted stage of Gonyaulax spinifera (Claparede and Lachmann, 1859) Diesing, 1866, according to Wall and Dale, 1968.
Holotype: Deflandre and Cookson, 1955, pl.8, fig.5
Locus typicus: Princetown, Victoria, Australia
Stratum typicum: Middle Miocene
---------------------------------------------------------
Original diagnosis: Deflandre and Cookson, 1955, p.268
Characters of the genus: shell slightly elliptical, with numerous processes of which the longest approaches half the diameter of the shell. Processes trifurcate, the extremities of the 3 branches joined to neighbouring processes by delicate filaments.
Dimensions: Diameter of shell c. 31 Ám, overall diameter 61 by 56 Ám, length of processes 13-15 Ám (Holotype).
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Comments: Wrenn 1988, p. 139-140
Nematosphaeropsis balcombiana Deflandre & Cookson 1955 (see Plate 7, fig. 3) was described as having a slightly elliptical "shell" (central body) bearing numerous processes, the longest of which approaches half the diameter of the central body. The trifurcate processes are joined distally to neighboring processes by "delicate filaments" (trabeculae). The central body of the holotype is 31 Ám in diameter and the processes range from 13- 15 Ám in length. The distinctive morphologic features of N. balcombiana are its broad, often proximally branched processes, delicate trabeculae of variable width, and the parasutural ridges that clearly express
paratabulation . Wall (1965, 1967) reported N. balcombiana from the Woods Hole, Massachusetts area and the Caribbean Sea. Those from the Woods Hole area he suggested might be identical with Pterosperma
labyrinthus Ostenfeld 1903. This seems unlikely in light of earlier discussions, though this report is hard to assess because no specimens were illustrated. The Caribbean Sea specimens were illustrated (Wall, 1967) and are considered here to be specimens of N. rigida sp. nov. Wall (1967) also reported, but did not illustrate, a "small variety" of what he designated N. balcombiana. These specimens may actually have been specimens of N. Iemniscata.
Comparison. Wrenn 1988, p. 139-140: N. balcombiana differs from:
N. downii by being smaller, having thin, delicate trabeculae and broad, proximally branched processes that are joined proximally by strongly developed parasutural ridges;
N. elegantulum by having clearly expressed paratabulation on the central body and by lacking the complex distal process branching of the latter;
N. Iativittatus sp. nov. by having thin, delicate trabeculae of variable width, broad, proximally branched processes and clearly expressed paratabulation;
N. Iemniscata by having shorter processes that are broad-based and can be branched proximally and by the well-developed parasutural ridges connecting process bases;
N. ? philippotii by having strongly developed parasutural ridges on the central body and broader
processes;
N. pustulosa by having paratabulation expressed by parasutural ridges and by having an elliptical
central body;
N. quinquetrum by having paratabulation expressed by parasutural ridges and by having an
elliptical central body;
N. rigida sp. nov. by having thin delicate trabeculae, broad-based processes that are branched proxi-
mally and well-developed parasutural ridges connecting process bases;
N. scala by having delicate trabeculae that are variable in width and that are not joined to each
other by cross-strands; and
N. singularis by having well-developed parasutural ridges
Stratigraphic Range. N. balcombiana was described from the middle Miocene of Australia. Reported rare occurrences in the Eocene London Clay of England (Williams, 1966; Williams and Downie, 1966) were not illustrated and cannot be assessed.